How to Determine the Age of Ginseng Plants

Ginseng plants can be aged before being harvested using two methods: by counting the number of leaves (also known as prongs) and/or counting the number of bud scale scars on the root.

Most ginseng plants produce 2 prongs when they reach 3 to 4 years of age. Ginseng plants add a third prong between 5 and 9 years of age, with the majority of them doing so when they are 7 years old. Most States with wild ginseng harvest programs already have regulations in place that prohibit the harvest of plants with less than three prongs (that is, harvested plants must be at least 5 years old).

The age of a ginseng plant can also be determined by counting the number of bud scale scars on the root. A single scar is produced every autumn after the plant's stem falls. Ginseng roots can be aged before their removal from the ground by simply removing the soil around the area where the plant's stem joins the root, and then counting the bud scale scars. Following is a more technical description on aging ginseng from Anderson et al. (1984).

Aging ginseng roots

Each year's growth adds a now basal internode to the length of the rhizome. Evidence of the first year's growth is marked by a dormant bud at the cotyledonary node, where the rhizome joins the root collar. Each subsequent year's growth is marked by a circle of bud scale scars. Following abscission of the aerial shoot, a dormant bud persists above the second bud scale scar. However, because of the short internode distance between bud scales, and the distichous arrangement of the scales, the dormant bud appears to be above the circle of bud scales scars. Adjacent to each of the small, dormant buds is the shelf-like aerial shoot abscission scar, Fig. 5. Thus, following shoot abscission there are two buds adjacent to the aerial shoot scar. One is the small bud which normally remains dormant and the other is the larger bud which will give rise to an aerial shoot during the next growing season. As previously noted, the larger bud also contains bud primordia for the two buds that develop during the next growing season.

Aerial shoot abscission zone scars may be almost overgrown and obliterated by the enlargement of the adjacent aerial shoot. Each successive dormant bud and aerial shoot bud are rotated on the shoot axis almost 90° clockwise (CW) or counter clockwise (CCW) from the previous one. This is because the plane of the distichous aerial shoot bud scales is 180° from the plane of the bud scale in whose axil it formed. Thus, successive sympodia are oriented 90° apart. Based on the morphology of the rhizomes examined, each year's growth seems to have an equal chance of being oriented 90° CW or CCW from the current year. This pattern is especially consistent for plants that have erect rhizomes.

To accurately age a plant the connection at the rhizome root collar is used to mark the first the year's growth. Growth in subsequent years is marked by a circle of bud scale scars and a "dormant bud."

It remains unknown how old a ginseng plant may become, although 20-30 years does not appear unreasonable. It would be possible for the primary root and older portions of the rhizome to be destroyed. Such a plant may continue to grow with adventitious roots assuming the storage and absorption functions. However, in all the plants we have observed, up to 20 years in age, there is an easily identifiable primary root.

Dormant buds may differentiate to form a new aerial shoot, if the rhizome above the bud or the uppermost bud is destroyed, Fig. 6. This can result in errors in aging the rhizome and, depending on the injury, this may result in a large plant appearing younger than its actual age. So, while it does not seem probable that the type of secondary growth observed in the rhizome of ginseng could continue indefinitely, there is no restriction to the plant's continued growth. Although, beyond a certain age, it would be increasingly unlikely that the correct age of the plant could be morphologically confirmed. Only the suppression of the dormant buds prevents the rhizome from branching and forming a clonal cluster similar to many rhizomatous perennials.

Figure 5. Camera lucida drawing of a 10-year-old ginseng rhizome. Starting at the root collar (RC) the arrows on the right indicate the top of the basal internode of each successive year's growth. A portion of the aerial shoot (AS) produced during the current year is attached. Note the size difference between next season's aerial shoot bud (ASB) and the dormant bud on the opposite side of the aerial shoot. Bar = 1 cm.

Figure 6. Camera lucida drawing of a 7-year-old ginseng rhizome. Arrows on the left show two year's growth of the original rhizome, whose third season's aerial shoot bud aborted. The dormant bud located at the root collar developed a new rhizome in the third year which has continued growth in four subsequent years (AR = adventitious root), (AS = aerial shoot). Bar = 1 cm.

Reference
Anderson, R. C., J. S. Fralish, J. Armstrong, and P. Benjamin. 1984. Biology of ginseng, Panax quinquefolius, in Illinois. Illinois Department of Conservation, Division of Forest Resources and Natural Heritage, Springfield, Illinois. 32 pp.